Do iPhone 3gs cases fit iPhone 4

The iPhone 3gs has 3 sensors on the front. A proximity sensor deactivates the display when the device is brought near the face, n ambient light sensor adjusts the display brightness, & a 3-axis accelerometer senses the orientation of the phone. Wow!

No the iPhone 4 has different dimensions, including the back which has a flat back, compared to the curved back of the 3g and 3gs. Apple is still offering free cases for new iPhone 4 purchases before September 30th.